https://www.amazon.com/dp/B075SHJR5W/ref=cm_sw_r_cp_apa_fabt1_cDcSFbDQG4Q7C?_encoding=UTF8&psc=1

I bought a bunch of these when my daughter got her brace. They're stretchy and seamless so they lay flat on her skin. They also are pretty decent at moisture wicking but not very breathable. My co-mom bought some bamboo material tanks that Little Miss loves cause they're super soft, but they bunch under the brace. It's a trade off.

Really the most important thing is that they change it every day (seems obvious, right? 🙄).